Flowers are left next to a police roadblock where police are investigating the death of seven people in suspected murder-suicide in Osmington, east of Margaret River, 11 May 2018.
Photograph: Richard Wainwright/AAP

Hope Forest, South Australia, 6 September 1971

Heather Bartholomew was sleeping when her estranged husband Clifford Bartholomew crept into their farmhouse south of Adelaide and struck her in the head with a mallet. Instead of rendering her unconscious, as he later claimed to have intended, his wife awoke, screaming. He shot her in the head with a .22 rifle. Then he shot his seven children, who were between four and 19 years old, his sister-in-law and his 18-month-old nephew.

What happened in Hope Forest claimed 10 lives, making it Australia’s worst familicide on record. High victim counts were also recorded in the Majka (1957), Darnley (1964), Ross (1982), May (1996) and, now, the Miles (2018) family murders. In each of these cases, seven people died, including the perpetrators who completed suicide. In all but one of these crimes, guns were involved.

The deaths of three generations of the Miles family at a rural property south of Perth on Friday is the country’s worst mass shooting in 22 years. Following the 1996 Port Arthur massacre, prime minister John Howard introduced controversial restrictions on the use and ownership of guns.

After each mass shooting in the United States, Australia is held up as a shining example of the benefits of gun control. So with a hint of tit-for-tat, some in the US have suggested the Miles murder-suicide proves gun control doesn’t work. In an article for the Washington Examiner, Siraj Hashmi said that “while some data suggest that super-strict gun control has cut down on gun violence and gun-related deaths in some cases, there’s still no guarantee that you’re safe.”

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But you’re certainly safer. A paper published in March 2018 in the Annals of Internal Medicine examined Australian firearms deaths between 1979 and 2013 to see whether gun law reform had any effect. It showed that while 13 mass shootings took place in the 18 years leading up to and including the Port Arthur massacre, none had occurred in the 22 years since. The authors calculated that the odds of this happening by chance were one in 200,000. (In other words, it was no coincidence.) Yet it wasn’t just public mass shootings which declined post-1996. Shootings of multiple family members in a single event did as well.

The annihilation of an entire family by one of its adult members has always been seen as something unspeakable. Coroners delivered sparse, stripped-back findings, as if the whole business was simply too distasteful for words. Barriers to better understanding of familicide include its statistical rarity, and the fact that such events typically leave behind few survivors to help shed light on what happened.

Because of these challenges, researchers working in this area frequently use newspaper articles as source materials. So it was that I, too, found myself trawling through 67 years of Australian newspapers for a Master of Psychology (Forensic) dissertation. I identified 141 Australian cases of familicide from 1950 to 2017, which involved 416 deaths in total. While the purpose of the study was the creation of a typology of perpetrators, the data did yield some interesting facts about gun-related familicides.

So how could something like this happen in gun-averse Australia?

Overall, shooting was the most common method of killing one’s family, with stabbing second, and gassing third. Yet only 12 of the 47 total gun-related events occurred after 1996. A closer look at the balance of events pre- and post-1996 revealed that while guns were used by more than half (56.7%) of all perpetrators prior to 1996, they were used by only 16% of perpetrators thereafter. From 1996 onwards, stabbing overtook shooting as the most common method of killing and was used by more than one-third (35.8%) of perpetrators. When you consider that Australia’s population roughly trebled over that period, from eight million in 1950 to almost 25 million in 2017, the shift in methods becomes all the more remarkable.

Recognition is growing in Australia and the US that the majority of mass shootings happen behind closed doors. The dominant media narrative features a disgruntled loner indiscriminately spraying bullets at whomever happens to cross their path. However, Everytown for Gun notes that 54% of mass shootings in the US are related to domestic or family violence. The National Coalition Against Domestic Violence claims the presence of a gun in a domestic violence situation increases the risk of homicide by 500%. And almost always, the shooter is a man.

Watch Hill farm, New South Wales, 9 September 2014

Disability support worker Lorraine Bourke arrived at the Hunt family farmhouse to start her shift. A car accident two years earlier had left Kim Hunt with lingering physical injuries. As Bourke walked along the path leading to the house, she found Kim lying on the ground, blood pooling around her head. Attending police located the bodies of the three children in separate bedrooms in the house. A day later, the body of Kim’s husband, Geoff Hunt, was located. After murdering his family, he had driven half a kilometre to a dam on the property, staggered into the water and put the muzzle of the gun in his mouth.

This murder-suicide amply demonstrates that guns aren’t just dangerous in homes marred by domestic violence. An inquest into the Hunt case revealed that there was no known history of domestic violence. Rather, the coroner determined that the murder-suicide was driven by Geoff Hunt’s depressive beliefs. His primary intent was suicide. Yet his wife and children were also killed due to an “egocentric delusion” in which he believed he was ending his wife’s misery, and that the children “would be better off dying than living without him”.

So how could something like this happen in gun-averse Australia? As a farmer, Geoff Hunt had access to firearms. So too did Peter Miles, the grandfather who is suspected to have shot his wife, daughter, grandchildren and himself on Friday. In their method, and the scale of their lethality, these two murder-suicides most resemble pre-1996 events. Though greater awareness of the risks of gun access in rural areas has helped reduce deaths, ongoing vigilance is required. For example, Kim Hunt’s disclosure of suicidal ideation a year before she died led police officers to confiscate two long arm rifles. The weapons were returned two months later, after Kim Hunt’s mental health had improved.

Fountaindale, New South Wales, 1 February 2015

Truck driver Colin Cooper was travelling along a winding section of Enterprise Drive when he noticed a silver Toyota Corolla ahead of him. Cooper watched the car arc to the left and crash into a tree. A subsequent inquest determined that the driver of the car, Darren Milne, had not only deliberately driven the car at high speed into a tree. An engineer, Milne had meticulously planned the event, filming 10 practice runs on his dash cam, visiting the site two days before the crash, and wiring canisters with fuel at points throughout the car, so if the crash didn’t kill the car’s occupants, the subsequent inferno would. Killed along with Milne was his wife, their unborn baby of 30 weeks’ gestation, and his 11-year-old son. His younger son survived with serious injuries.

There is the argument that family murderers, deprived of easy access to firearms, will simply resort to other, more creative, and potentially messier methods. It’s true. Like Milne, some will. But shifting away from case specifics and towards aggregate data, there is no evidence to suggest that taking away firearms results in people substituting other means. A 2016 article published in JAMA (Journal of the American Medical Association) specifically addressed this question by comparing Australian firearm versus non-firearm suicides and homicides from 1979-2013. The authors found that firearms deaths were already declining prior to gun law reform, but that this rate of decline accelerated from 1997 onwards. Meanwhile, suicides and homicides undertaken via alternative means had been increasing prior to gun law reform, but began to decrease post-1996. The authors point out that factors other than gun laws, such as improved emergency care, and speedier means of accessing it courtesy of mobile phones, may have contributed to these results. But they concluded that there was “no apparent substitution to other lethal methods, or if there was substitution, it may have been into less lethal methods”.

For lethal methods matter. According to the Monash University Accident Research Centre, the lethality rate of suicide via firearms is approximately 85%, which exceeds all other methods. A 1998 paper published in the Australian & New Zealand Journal of Psychiatry identified that less lethal methods reduce suicide rates in several ways. They decrease the odds that attempts progress to completion. They provide a greater opportunity for those pondering a dark pathway to change their minds, or for bystanders to intervene. Restricting gun access is analogous to constructing barriers at notorious suicide jumping-off spots. It provides a life-saving pause between impulse and action.

About one-third of perpetrators in my study used multiple methods to kill their victims. Sometimes, they did so to guarantee the victims’ deaths, or because their initial attempt failed. Firearms perpetrators sometimes resorted to additional methods, but for different reasons. Several shooters lit fires, perhaps in misguided attempts to destroy the evidence of their crimes. But perpetrators who shot their families were less likely to use additional methods to kill their victims. Armed with a gun, they didn’t need any backup.

•In Australia, the crisis support service Lifeline is on 13 11 14 and the national family violence counselling service is on 1800 737 732. In the UK, Samaritans can be contacted on 116 123 and the domestic violence helpline is on 0808 2000 247. Other international helplines can be found at www.befrienders.org

• Denise Cullen is a prison psychologist and journalist based in Brisbane